Following completion of the trial period for inventory reporting
and review, annual review of individual inventories of each Annex I Party became mandatory in 2003
decision 19/CP.8). The
UNFCCC Annex I inventory review guidelines, revised in 2014 ( decision
13/CP.20) , ensure that the COP is provided with an objective, consistent, transparent,
thorough and comprehensive technical assessment of the quantitative and qualitative inventory
information submitted annually by Annex I Parties. Annual review ensures that adequate consideration
is given to recalculations and emission trends over time.

The review of greenhouse gas (GHG) inventories comprises two stages. Each stage complements the
previous one. Review reports are prepared and published on the secretariat web site.

Initial assessment by the secretariat: a standardized set of data comparisons mainly based on the
common reporting format (CRF) data, aiming to examine that each Annex I Party has submitted a
consistent, complete and timely annual inventory in the correct format, including the national
inventory report (NIR) and the CRF tables, and to identify issues for further consideration during
the review of individual inventories. Status reports for each Party are published at this stage while
assessment reports are available to Parties and expert review teams (ERTs);

Review of individual annual inventories by ERTs: ERTs examine the data, methodologies and
procedures used in preparing the national inventory. ERTs are required to pay particular
attention to key categories, areas of the inventory where issues have been identified and
recommendations made in previous reviews, or stages of the review, progress in the implementation of
the planned improvements, or where recalculations or other changes have been reported by the Annex I
Party. This is the most detailed review stage. Individual review reports are published for each
Party.

Three operational approaches may be used during the second stage of the technical review, namely desk
reviews, centralized reviews or in-country reviews.

Protection of confidential inventory information

Guidance on the use of confidential information by ERTs is addressed in the UNFCCC Annex I inventory
review guidelines under the Convention. In addition, by decision 12/CP.9,
Parties adopted a code of practice for the treatment of confidential information in the technical
review of greenhouse gas inventories from Annex I Parties. In 2004 the secretariat developed, and has
since been implementing procedures to implement the code of practice. These procedures cover
submission, processing and handling by the secretariat of any information designated as confidential
by an Annex I Party, and the granting of access by ERTs to this information.

Expert review teams

The annual inventory review process requires the participation of over 150 skilled experts per year.
Members of the expert review teams (ERTs) are selected on an ad hoc basis from the UNFCCC roster of
experts nominated by Parties and intergovernmental organizations. The secretariat selects experts to
ensure coverage of all inventory sectors, and to achieve an overall balance in the participation of
experts from Annex and non-Annex I Parties. Two lead reviewers, one each from an Annex I and a
non-Annex I Party, guide the work of the teams. Lead reviewers ensure that the reviews in which they
participate are performed by each ERT according to the relevant review guidelines and consistently
across Parties.

Participation of experts nominated by Parties helps to ensure that the review results are thorough,
objective, credible and recognized by Parties. In addition, it helps build inventory capacity across
all Parties. During the review, reviewed Parties receive technical feedback from other experts (the
members of the ERTs) that enables them to further improve their inventories. Likewise, experts who
participate in reviews gain knowledge of inventory practices of other Parties, which they can take
home and apply, as appropriate, to their own inventories.

All members of expert review teams participating in the technical review of greenhouse gas
inventories must sign an agreement for expert review services. The agreement specifies the
responsibilities and appropriate conduct for expert review team members, in particular with respect
to the protection of confidential inventory information, as determined by the COP. Any new review
team members must also successfully complete training on how to perform a review and pass the
appropriate examinations.

The COP requested the secretariat to facilitate meetings of lead reviewers for GHG inventories to
facilitate the work of lead reviewers in fulfilling their task to ensure consistency in the reviews
across Parties. Lead reviewers are also collectively required to prepare an annual report to the
SBSTA, containing suggestions on how to improve the quality, efficiency and consistency of the
reviews. The secretariat has organized these meetings annually since 2003. The conclusions of these
meetings are presented through the following links:

Guidelines for the technical review of information reported under the Convention related to greenhouse gas
inventories, biennial reports and national communications by Parties included in Annex I to the
Convention”
(decision 13/CP.20)